/***
 * ASM: a very small and fast Java bytecode manipulation framework Copyright (c) 2000-2011 INRIA,
 * France Telecom All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted
 * provided that the following conditions are met: 1. Redistributions of source code must retain the
 * above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions
 * in binary form must reproduce the above copyright notice, this list of conditions and the
 * following disclaimer in the documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of its contributors may be used to
 * endorse or promote products derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
 * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package com.googlecode.aviator.asm;

/**
 * A visitor to visit a Java class. The methods of this class must be called in the following order:
 * <tt>visit</tt> [ <tt>visitSource</tt> ] [ <tt>visitOuterClass</tt> ] ( <tt>visitAnnotation</tt> |
 * <tt>visitAttribute</tt> )* ( <tt>visitInnerClass</tt> | <tt>visitField</tt> |
 * <tt>visitMethod</tt> )* <tt>visitEnd</tt>.
 *
 * @author Eric Bruneton
 */
public abstract class ClassVisitor {

    /**
     * The ASM API version implemented by this visitor. The value of this field must be one of
     * {@link Opcodes#ASM4}.
     */
    protected final int api;

    /**
     * The class visitor to which this visitor must delegate method calls. May be null.
     */
    protected ClassVisitor cv;

    /**
     * Constructs a new {@link ClassVisitor}.
     *
     * @param api the ASM API version implemented by this visitor. Must be one of
     *            {@link Opcodes#ASM4}.
     */
    public ClassVisitor(final int api) {
        this(api, null);
    }

    /**
     * Constructs a new {@link ClassVisitor}.
     *
     * @param api the ASM API version implemented by this visitor. Must be one of
     *            {@link Opcodes#ASM4}.
     * @param cv  the class visitor to which this visitor must delegate method calls. May be null.
     */
    public ClassVisitor(final int api, final ClassVisitor cv) {
        if (api != Opcodes.ASM4) {
            throw new IllegalArgumentException();
        }
        this.api = api;
        this.cv = cv;
    }

    /**
     * Visits the header of the class.
     *
     * @param version    the class version.
     * @param access     the class's access flags (see {@link Opcodes}). This parameter also indicates if
     *                   the class is deprecated.
     * @param name       the internal name of the class (see {@link Type#getInternalName()
     *                   getInternalName}).
     * @param signature  the signature of this class. May be <tt>null</tt> if the class is not a
     *                   generic one, and does not extend or implement generic classes or interfaces.
     * @param superName  the internal of name of the super class (see {@link Type#getInternalName()
     *                   getInternalName}). For interfaces, the super class is {@link Object}. May be
     *                   <tt>null</tt>, but only for the {@link Object} class.
     * @param interfaces the internal names of the class's interfaces (see
     *                   {@link Type#getInternalName() getInternalName}). May be <tt>null</tt>.
     */
    public void visit(int version, int access, String name, String signature, String superName,
                      String[] interfaces) {
        if (cv != null) {
            cv.visit(version, access, name, signature, superName, interfaces);
        }
    }

    /**
     * Visits the source of the class.
     *
     * @param source the name of the source file from which the class was compiled. May be
     *               <tt>null</tt>.
     * @param debug  additional debug information to compute the correspondance between source and
     *               compiled elements of the class. May be <tt>null</tt>.
     */
    public void visitSource(String source, String debug) {
        if (cv != null) {
            cv.visitSource(source, debug);
        }
    }

    /**
     * Visits the enclosing class of the class. This method must be called only if the class has an
     * enclosing class.
     *
     * @param owner internal name of the enclosing class of the class.
     * @param name  the name of the method that contains the class, or <tt>null</tt> if the class is
     *              not enclosed in a method of its enclosing class.
     * @param desc  the descriptor of the method that contains the class, or <tt>null</tt> if the class
     *              is not enclosed in a method of its enclosing class.
     */
    public void visitOuterClass(String owner, String name, String desc) {
        if (cv != null) {
            cv.visitOuterClass(owner, name, desc);
        }
    }

    /**
     * Visits an annotation of the class.
     *
     * @param desc    the class descriptor of the annotation class.
     * @param visible <tt>true</tt> if the annotation is visible at runtime.
     * @return a visitor to visit the annotation values, or <tt>null</tt> if this visitor is not
     * interested in visiting this annotation.
     */
    public AnnotationVisitor visitAnnotation(String desc, boolean visible) {
        if (cv != null) {
            return cv.visitAnnotation(desc, visible);
        }
        return null;
    }

    /**
     * Visits a non standard attribute of the class.
     *
     * @param attr an attribute.
     */
    public void visitAttribute(Attribute attr) {
        if (cv != null) {
            cv.visitAttribute(attr);
        }
    }

    /**
     * Visits information about an inner class. This inner class is not necessarily a member of the
     * class being visited.
     *
     * @param name      the internal name of an inner class (see {@link Type#getInternalName()
     *                  getInternalName}).
     * @param outerName the internal name of the class to which the inner class belongs (see
     *                  {@link Type#getInternalName() getInternalName}). May be <tt>null</tt> for not member
     *                  classes.
     * @param innerName the (simple) name of the inner class inside its enclosing class. May be
     *                  <tt>null</tt> for anonymous inner classes.
     * @param access    the access flags of the inner class as originally declared in the enclosing
     *                  class.
     */
    public void visitInnerClass(String name, String outerName, String innerName, int access) {
        if (cv != null) {
            cv.visitInnerClass(name, outerName, innerName, access);
        }
    }

    /**
     * Visits a field of the class.
     *
     * @param access    the field's access flags (see {@link Opcodes}). This parameter also indicates if
     *                  the field is synthetic and/or deprecated.
     * @param name      the field's name.
     * @param desc      the field's descriptor (see {@link Type Type}).
     * @param signature the field's signature. May be <tt>null</tt> if the field's type does not use
     *                  generic types.
     * @param value     the field's initial value. This parameter, which may be <tt>null</tt> if the field
     *                  does not have an initial value, must be an {@link Integer}, a {@link Float}, a
     *                  {@link Long}, a {@link Double} or a {@link String} (for <tt>int</tt>, <tt>float</tt>,
     *                  <tt>long</tt> or <tt>String</tt> fields respectively). <i>This parameter is only used
     *                  for static fields</i>. Its value is ignored for non static fields, which must be
     *                  initialized through bytecode instructions in constructors or methods.
     * @return a visitor to visit field annotations and attributes, or <tt>null</tt> if this class
     * visitor is not interested in visiting these annotations and attributes.
     */
    public FieldVisitor visitField(int access, String name, String desc, String signature,
                                   Object value) {
        if (cv != null) {
            return cv.visitField(access, name, desc, signature, value);
        }
        return null;
    }

    /**
     * Visits a method of the class. This method <i>must</i> return a new {@link MethodVisitor}
     * instance (or <tt>null</tt>) each time it is called, i.e., it should not return a previously
     * returned visitor.
     *
     * @param access     the method's access flags (see {@link Opcodes}). This parameter also indicates if
     *                   the method is synthetic and/or deprecated.
     * @param name       the method's name.
     * @param desc       the method's descriptor (see {@link Type Type}).
     * @param signature  the method's signature. May be <tt>null</tt> if the method parameters, return
     *                   type and exceptions do not use generic types.
     * @param exceptions the internal names of the method's exception classes (see
     *                   {@link Type#getInternalName() getInternalName}). May be <tt>null</tt>.
     * @return an object to visit the byte code of the method, or <tt>null</tt> if this class visitor
     * is not interested in visiting the code of this method.
     */
    public MethodVisitor visitMethod(int access, String name, String desc, String signature,
                                     String[] exceptions) {
        if (cv != null) {
            return cv.visitMethod(access, name, desc, signature, exceptions);
        }
        return null;
    }

    /**
     * Visits the end of the class. This method, which is the last one to be called, is used to inform
     * the visitor that all the fields and methods of the class have been visited.
     */
    public void visitEnd() {
        if (cv != null) {
            cv.visitEnd();
        }
    }
}
